SCC-SG Series Strain Gage Modules User Guide
Contents
1. 2 3 4 DAQ device AI X 8 5 SCH Es 6 DAQ device AI GND 7 DAQ device PO X 8 E E 9 5 V 5 V 10 GND G ND 11 A GND A GND 12 REF 5 V 13 15 V 15 V 14 15 V 15 V 15 16 17 AI X from first stage 18 AI X 8 from first stage 19 AI X from first stage 20 AI X 8 from first stage SCC SG Series Strain Gage Modules User Guide 38 ni com Theory of Operation Strain Gage Theory This section contains information about Wheatstone bridges and the different strain gage bridge configuration types Wheatstone Bridges All strain gage configurations are based on the concept of a Wheatstone bridge A Wheatstone bridge is a network of four resistive legs One or more of these legs can be active sensing elements Figure 23 shows a Wheatstone bridge circuit diagram Figure 23 Basic Wheatstone Bridge Circuit Diagram The Wheatstone bridge is the electrical equivalent of two parallel voltage divider circuits R and Ry compose one voltage divider circuit and R4 and Rs compose the second voltage divider circuit The output of a Wheatstone bridge is measured between the middle nodes of the two voltage dividers V cw Physical phenomena such as a change in strain applied to a specimen or a temperature shift changes the resistance of the active sensing elements in the Wheatstone bridge The Wheatstone bridge configuration is used to2. Full Bridge SCC SG04 24 O DAQ Device a x 100 AL EEN S A S O V SCC SG11 QH O DE de S AN S SS e Po x S 8 i OI a 1 The SCC SG24 provides a 10 VDC excitation current Figure 18 Full Bridge Shunt Calibration Configuration Using SCC SG11 and SCC SG04 24 One Channel to Shunt R4 Each screw terminal of the SCC SG11 is labeled by pin number lt 1 4 gt The SCC SG11 contains two shunt calibration circuits each consisting of a precision 301 KQ resistor and a relay contact The circuits are independent of each other but the relay contacts are controlled together by E Series DAQ device digital output channel PO X The value of X is determined by the number of the SC 2345 socket J X 9 where you plug in the SCC SG11 When PO X is set to 1 on the E Series DAQ device the shunt calibration circuits are enabled and the LED indicator on the SCC SG11 is lit When PO X is set to 0 the circuits are disabled and the LED indicator on the SCC SG11 is off At startup or reset the circuits are disabled When the circuits are enabled the shunt calibration resistor is connected to the SCC SG11 screw terminals This allows you to place a resistor in parallel with a strain gage element SCC SG Series Strain Gage Modules User Guide 22 ni com B Note Shunt calibration with the SCC SG11 is not a dual stage configuration You
3. National Instruments Corporation 49 SCC SG Series Strain Gage Modules User Guide B Note The nulling range of the SCC SGOX and SCC SG24 is dependent on the excitation voltage active strain gage element value and the value of the nulling resistor You can change the nulling range of the offset nulling circuitry for each channel by replacing its nulling resistor with a nulling resistor of another value The value of the nulling resistors on the SCC SGOX and SCC SG24 is 30 kQ These nulling resistors are socketed for easy replacement Refer to the Replacing Resistors section for more information on replacing resistors To determine the nulling range use the following formula while referring to Figures 19 20 or 21 _ 4 Vex Heckt Runn Ry ene H EE 2 Ranch rann Ry where Ry is the nominal active strain gage element resistance value Rs is either the value of the quarter bridge completion resistor or the nominal resistance of the second active strain gage element Refer to Figures 19 20 or 21 to locate the resistor in quarter half and full bridge configurations Rwuz is the value of the nulling resistor Vex is the excitation voltage For example for a quarter bridge configuration using the SCC SG01 R 1200 R 1200 Rot 30 KQ Vex 2 5 VDC then VNULLING 2 5 mV LabVIEW National Instruments NI ni com and NI DAQ are trademarks of National Instruments Corporation Product a
4. help measure the small variations in resistance that the sensing elements produce corresponding to a physical change in the specimen For more information on strain gage Wheatstone bridge configurations refer to the Strain Gages section You use different Wheatstone bridge configurations for different tasks The following sections provide information that should help you determine what bridge configuration type to use how it works and if it is the right configuration type for your task O National Instruments Corporation 39 SCC SG Series Strain Gage Modules User Guide B Note Normally load force pressure and torque sensors are arranged in full bridge Wheatstone bridge configurations similar to strain gage full bridge configurations If you are measuring load force pressure or torque use the SCC SG04 24 Strain Gages Strain gage configurations are arranged as Wheatstone bridges The gage is the collection of all of the active elements of the Wheatstone bridge There are three supported types of strain gage configurations quarter half and full bridge The number of active element legs in the Wheatstone bridge determines the kind of bridge configuration Refer to Table 2 to see how many active elements are in each configuration Table 2 Strain Gage Configurations Configuration Number of Active Elements Quarter bridge 1 Half bridge 2 Full bridge 4 Each of these three configurations is subdivided
5. a note which alerts you to important information This icon denotes a caution which advises you of precautions to take to avoid injury data loss or a system crash When this symbol is marked on the product refer to the Read Me First Safety and Radio Frequency Interference document shipped with the product for precautions to take When symbol is marked on a product it denotes a warning advising you to take precautions to avoid electrical shock When symbol is marked on a product it denotes a component that may be hot Touching this component may result in bodily injury Bold text denotes items that you must select in software such as menu items and dialog box options Bold text also denotes parameter names Italic text denotes variables emphasis a cross reference or an introduction to a key concept This font also denotes text that is a placeholder for a word or value that you must supply Text in this font denotes text or characters that you should enter from the keyboard sections of code programming examples and syntax examples This font is also used for the proper names of disk drives paths directories programs subprograms subroutines device names functions operations variables filenames and extensions Data acquisition DAQ device refers to all entry level basic and full featured E Series multifunction DAQ devices SC 2345 refers to both the SC 2345 connector block and the SC 2345 with configurable connecto
6. into multiple configuration types The orientation of the active elements and the kind of strain measured determines the configuration type NI supports seven configuration types in software However with custom software scaling you can use all Wheatstone bridge configuration types with any NI hardware product that supports the gage configuration type The supported strain gage configuration types measure axial strain bending strain or both You can use similar configuration types to measure torsional strain however NI software scaling does not support these configuration types It is possible to use NI products to measure torsional strain but to properly scale these configuration types you must create a custom scale in MAX or perform scaling in your software application SCC SG Series Strain Gage Modules User Guide 40 ni com Quarter Bridge Type This section provides information for the quarter bridge strain gage configuration type I The quarter bridge type I measures either axial or bending strain Axial Bending Figure 24 Quarter Bridge Type Measuring Axial and Bending Strain A quarter bridge type I has the following characteristics e A single active strain gage element is mounted in the principle direction of axial or bending strain e A passive quarter bridge completion resistor dummy resistor is required in addition to half bridge completion e Temperature variation in specimen decreases the accura
7. n E A EE e 29 Full Bridge Type A 29 Full Bridge Type M masine nn at 29 Specifications Ee Mani wes E E R EE AREE 30 SCC SGOX Strain Gage Input Modules AAA 30 Strain Gage Bridge Confguraton 30 RENE 30 Transfer Characteristics hreini 30 Amplifier Characteristics e 31 LEE 31 Strain Gage Bridge Compnlettons 31 Completion Accuracy erre 31 Power Requirements iodid ri 32 SCC SG24 Strain Gage Input Module 32 Analog E 32 Transfer Characteristics Nasii 32 Amplifier Characteristics 33 Dy namie e g Ea ne eS 33 el LN EE 33 SCC SG Series Strain Gage Modules User Guide 2 ni com Null Compensation een 33 Le e 34 Power Requirements eee 34 SCC SG11 Shunt Calibration Module 34 Digital DO DE 34 Shunt Calibration sic scessscssesecssccateaccssadsscovasescsseseasestsessoahesverscooes 34 Power Reouremente eae 35 SCC SGXX Strain Gage Input Modules A 35 Maximum Working Voltage 35 Physical ege uetkkde Ee ei staged Adeudea Get ca a ES 35 Environmental 3 et ss cera maine maresia arracazo A osebetene 36 KT EE 36 Electromagnetic Compatibility eeeeseeeseeseceeeeseeaeenss 36 CE Compliance ssa dao sees gedd ees SEENEN 36 SCC SGXX Module Pin Assignment eeseeseeeeeeseeeeeeseeeees 37 Theory of Operation nenna bigesasasstiscaginde iu nb E E 39 Strain Gage Theory aneron eege eis etna eek EN e 39 Whe
8. of strain with one on one side of the strain specimen top the other on the opposite side bottom Compensates for temperature Rejects bending strain Compensates for the aggregate effect on the principle strain measurement due to the Poisson s ratio of the specimen material Compensates for lead resistance Sensitivity at 1 000 us is 1 3 mVoyr Vegx input Used with the SCC SG04 24 47 SCC SG Series Strain Gage Modules User Guide Signal Conditioning Theory The SCC SGXX modules all contain some form of signal conditioning This signal conditioning can greatly increase the accuracy of your measurements The following types of signal conditioning are provided by the SCC SGXX e Filtering e Amplification e Excitation e Bridge completion e Offset nulling adjustment e Shunt calibration Refer to the Filtering Amplification Excitation Bridge Completion Calibration and Shunt Calibration Using the SCC SG11 sections for more information about each type of signal conditioning Filtering Each channel on the SCC SGOX and SCC SG24 has an output lowpass filter The filter is a single pole buffered RC filter with a cutoff frequency of 1 6 kHz Amplification Each channel on the SCC SGOX and SCC SG24 has an instrumentation amplifier with a gain of 100 This amplifier improves signal measurements by boosting strain measurements typically approximately 100 mV to levels closer to the operating range of E Series DAQ de
9. rdtntg to confirm the signal names Refer to the SCC Quick Start Guide for general information about connecting input signals Each screw terminal on the SCC SGOX and SCC SG24 is labeled by pin number lt 1 6 gt The input stage of the SCC SG0X and SCC SG24 provides two differential analog input channels for measuring strain The input pins to the SCC SGOX and SCC SG24 differ for each module Pin 4 is a single ended channel routed to E Series DAQ device channel X 8 and SCC SG Series Strain Gage Modules User Guide 6 ni com Panelettes pin 6 is a single ended channel routed to E Series DAQ device channel X The value of X is 0 to 7 depending on the socket where you plug in the SCC SGOX and SCC SG24 J X 1 or J X 9 If you have an SCC carrier with configurable connectors you can install connectivity and interface panelettes to customize the SCC system Panelettes simplify signal connection to the SCC modules and eliminate the need to rewire signals to the screw terminals when you change the signal source The most common panelettes used with the SCC SGOX and SCC SG24 strain applications are the 9 pin D Subminiature DSUB MIL Spec and LEMO B Series SCC SG0X and SCC SG24 The various bridge configurations discussed in the Strain Gages section require different SCC modules The following sections discuss the bridge configuration types supported by each module and provide connection and electrical diagrams for the different b
10. 0 carrier refer to the SCC Quick Start Guide available for download at ni com manuals Installing the Module A Ei Caution Refer to the Read Me First Safety and Radio Frequency Interference document before removing equipment covers or connecting disconnecting any signal wires For information about the SC 2350 carrier refer to the SCC Quick Start Guide This section explains how to install the SCC SGXX in the SC 2345 carrier Note The SCC SGOX and SCC SG24 can act both as a single stage module and as the first stage of a dual stage configuration Plug the SCC SGOX or the SCC SG24 into any SC 2345 socket J X 1 where X is 0 to 7 and wire the bridge configuration signals to the module The socket you choose determines which E Series DAQ device channels receive the SCC SGOX or SCC SG24 signals as explained in the Connecting Strain Gage Input Signals section If you are using an SCC SG11 for shunt calibration plug it into any digital input output PO socket J X 9 where X is 0 to 7 This is not a dual stage configuration You must connect the SCC SG11 to the bridge configuration using additional wires Refer to the Shunt Calibration Using the SCC SG11 section Connecting Strain Gage Input Signals 3 Notes The SCC SG11 has a four terminal screw terminal receptacle Refer to the Shunt Calibration Using the SCC SG11 for more information about using the SCC SG11 The signal names have changed Refer to ni com info and enter
11. OX SCC SG24 and SCC SG11 module specific information is listed in separate sections followed by common information SCC SGOX Strain Gage Input Modules Strain Gage Bridge Configuration SCC SGO1 SCC SG02 SCC SG03 SCC SG04 Analog Input Number of strain gage channels Input signal ranges Overvoltage protection Input impedance Normal powered on Powered off or overload Bandwidth Input noise Transfer Characteristics Quarter bridge 120 Q Quarter bridge 350 Q Half bridge Full bridge 100 mV fixed gain of 100 on each channel 28 VDC powered on and powered off 10 MQ 10 KQ 1 6 kHz single pole RC filter 1 UV ims GALI WE 100 ET 0 8 of reading max Gain error temperature coefficient 5 ppm C Temperature range is 23 C 5 C 2 Temperature range is 0 to 50 C SCC SG Series Strain Gage Modules User Guide 30 ni com Offset ETOT anions ir na ego Offset error temperature coefficient Offset nulling adjustment range Nonlinearity Recommended warm up time Amplifier Characteristics Common mode rejection ratio CMRR Output range serseri Excitation Number of channels 5 uV post calibration 0 6 uV C1 2 5 mV RTI 10 ppm of full scale range 5 min 110 dB min 10 VDC max Strain Gage Bridge Completions Quarter bridge Half bridge Completion Accuracy Half bridge comple
12. STRUMENTS SCC SG01 02 Quarter Bridge Connection s sssesseseeeereerereseseesee 7 Quarter Bridge Type I eee eseesceeseceseeseeeseeaeeeeeeseeaes 8 SCC SG03 Half Bridge Connection o 10 Half Bride Type Tits cssscgscsecs iseen atlases 10 Half Bridge Type Meire sistem tects orina enie eaen 11 Quarter Bridge Type IL 12 SCC SG04 24 Full Bridge Connection ee eeeeeeeeeeeeeseeseeeees 14 PulleBridse Type Durrio a a E ER E o 14 Pult Bodee Cepeft EENS EENS 15 Full Bridge Type Mliios eearri aa 16 Calibration secs irei E aai EEPE EEEE E a 18 Using Shunt Calibration to Correct for Gain Error 18 Shunt Calibration Using the SCC SG11 oes 19 Replacing RESISLOLS q a ace ps aeee eaei E E ee A Eed 23 Replacing the Quarter Bridge Completion Resistors 23 Replacing the Nulling Resistors cceeseesceesceceseeeseeeeseceneeeeneeeenees 24 Replacing the Shunt Resistors seeeseeeeeeseeseeeseeeseeseenseens 24 Using the SCC SGXX Aere saves arara terial edd Ed 25 Converting Voltage Measurements to Units of Strain 25 Strain Equations aeni eege Eeer ER 26 Formulas and Variable Definitions 0 0 0 0 eee eee eeeereetees 27 Quartet Bridge Type Ls rss deed Malta nd idea no 27 Quarter Bridge Type UL 28 Half Bridse Ly perl o ques seccsbet ects sorgo rias LES einstein ies 28 Half Bridge Type ht eeh deed 28 Full Bd ee Type De eere anaien ieena
13. UE USER GUIDE SCC SG Series Strain Gage Modules This document discusses all of the mechanical electrical and scaling considerations of each strain gage configuration type supported by NI The SCC SG Series strain gage input modules SCC SGXX allow you to take quarter half and full bridge configuration strain measurements Use them as follows e SCC SGO1 for 120 Q quarter bridge configurations e SCC SGO02 for 350 Q quarter bridge configurations e SCC SG03 for half bridge configurations e SCC SG04 for full bridge configurations e SCC SG24 for at least 350 Q full bridge configurations Each module consists of two strain gage input channels offset nulling circuitry for each channel and an excitation circuit Each input channel includes an instrumentation amplifier with differential inputs and a fixed gain of 100 The SCC SGI1 is a shunt calibration module It contains two pairs of switches and resistors that you connect across strain gage elements where you want to perform shunt calibration Contents EE Eege EE ege 4 What You Need to Get Started A 5 Device Specific Information e 6 Installing the Module cssscssessesesssoreseessrsncseaeesessersnessceseeess 6 Connecting Strain Gage Input Stenale eeeeeeeeeeeees 6 Panglettes ssiiisss usa ieameserns senta ioo tees nine e A ee 7 SCE SGOX and SCC SG24 EE 7 Variable Definitions s siesess scan ceoteheadivisasstsicnessakbancens Ehe 7 Qr NATIONAL P IN
14. age connected to AI X and a two wire strain gage connected to SCC SG Series Strain Gage Modules User Guide Al X 8 If you are using a two wire strain gage short the AI X or AI X 8 screw terminal with the corresponding reference screw terminal R X and R X 8 The dummy resistor must be equal in value to the nominal resistance of the active strain gage element The SCC SGO1 contains one 120 Q quarter bridge completion resistor per channel The SCC SG02 contains one 350 Q quarter bridge completion resistor per channel One socketed quarter bridge completion resistor is internally connected between R X and analog ground The other is between R X 8 and analog ground These resistors are socketed for easy replacement Refer to the Replacing Resistors section for more information SCC SG03 Half Bridge Connection In a half bridge configuration you use two active strain gage elements A half bridge completion reference inside the SCC SG03 completes the bridge configuration There are two half bridge configuration types supported by NI software and one quarter bridge configuration type that requires half bridge completion The following sections describe how to connect half bridge strain gage configuration types I and II and quarter bridge strain gage configuration type II The SCC SG03 module label displays the icon shown in Figure 5 This icon label also represents the module bridge configuration Figure 5 SCC SGOS Ico
15. ation Connection Two Channels To connect a single full bridge configuration to a channel use four lead wires to connect the strain gages to screw terminals Vgx Vex AI X and AI X The two wires connected to Vgx and V gy provide excitation voltage to the strain gages The other two wires connected to AI X and Al X sense the output voltage of the strain gages Figure 14 shows two full bridge configurations using AI X and AI X 8 National Instruments Corporation 17 SCC SG Series Strain Gage Modules User Guide Calibration To null the voltage offset of the system including the bridge configuration complete the following steps 1 6 Configure and connect the bridge configuration to an SCC SGOX or SCC SG24 channel Create a strain gage virtual channel Refer to the SCC Quick Start Guide for more information Read the channel using a Measurement amp Automation Explorer MAX test panel or in another continuous acquisition application If you see a flat line in your test panel increase the channel input limits until you see a changing signal Try 50 000 ue While monitoring the channel input voltage rotate the appropriate trimming potentiometer wiper with a flathead screwdriver until you read 0 0 Next decrease the input range use 1 000 ue and repeat step 5 You have successfully nulled the system offset Using Shunt Calibration to Correct for Gain Error 1 Calculate the voltage
16. atstone Brid EE 39 Strain EE 40 Quarter Bridge Type Treier ee ee cance tarada vieron dee sa deities 41 Quarter Bridge Type U N 42 Half Bride Ttr is ias iso esse Bee a A ebe 43 Half Bridge D seess ENEE dee 44 EFull Bridge Type grs pas ia T asseio eee 45 Full Bridge Type IL 46 Full Bridee Lype M co esses stone pdgio sarro dd Nadie ce gado ta uses eens 47 Signal Conditioning Theory ees essceseseeceseeseeeseeseeeseeaeenss 48 Filtern a oie n a bua cando cy also ado nose tado Pont nada tert dana 48 Olne Le E 48 Excitation n asia tebe vite edd ARS Sd ea 48 Bridge Completion e 49 Theory of Cali bra sia eta e eegene eech 49 Offset Nulling Adjustment eee eeeeeeseceseeseeeeeeeeeaes 49 Nulling Range Adjustment eseeeeseceeeeeeeeseeseeeees 49 National Instruments Corporation 3 SCC SG Series Strain Gage Modules User Guide Conventions lt gt gt bold italic monospace DAQ device SC 2345 SCC The following conventions are used in this guide Angle brackets that contain numbers separated by an ellipsis represent a range of values associated with a bit or signal name for example AI lt 0 7 gt The symbol leads you through nested menu items and dialog box options to a final action The sequence File Page Setup Options directs you to pull down the File menu select the Page Setup item and select Options from the last dialog box This icon denotes
17. bration is performed or if lead length is very short lt 10 ft depending on the wire gauge For example 10 ft of 24 AWG copper wire has a lead resistance of 0 25 Q R is the shunt calibration resistor value U is the ratio of expected signal voltage to excitation voltage with the shunt calibration circuit engaged Parameter U appears in the equations for simulated strain and is defined by the following equation R U 4R 2R V is the voltage ratio that is used in the voltage to strain conversion equations and is defined by the following equation T cy Strained Fouls g Vix Quarter Bridge Type To convert voltage readings to strain units use the following equation 4y 3 M E ad strain a aa Rg To simulate the effect on strain of applying a shunt resistor across R4 use the following equation E 4U _ s GF 40 National Instruments Corporation 27 SCC SG Series Strain Gage Modules User Guide Quarter Bridge Type II To convert voltage readings to strain units use the following equation 4y S _ r m strain GFO 27 x 1 ZS To simulate the effect on strain of applying a shunt resistor across Ry use the following equation gt ae el GF 1 4U Half Bridge Type To convert voltage readings to strain units use the following equation deco no strain GFI v 2V v 1 Ss To simulate the effect on strain of applying a shunt resistor across Ry us
18. change expected from the introduction of the shunt calibration resistor using the following formula R Vrx Rscar R Vex AV EXPECTED RR eR Reape Ry 2 where Rscaz is the value of the shunt calibration resistor Ry is the nominal active strain gage element value Rs is either the value of a completion resistor or a second active strain gage element nominal value Vex 1s the excitation voltage For example for a quarter bridge configuration where R 1200 R 1200 Rscaz 301 KQ Vex 2 5 VDC Offset Voltage 0 VDC then AVeypecrep 0 2491 mV SCC SG Series Strain Gage Modules User Guide 18 ni com B Note Before completing step 2 null the system offset voltage Refer to the Calibration section for information on how to null the system offset voltage 2 Enable the shunt calibration circuit and measure the resulting voltage change AVyeasuRrED Use the following equation to calculate a correction factor that compensates for the DAQ system gain error AVexpeCTED _ F AV Weg MEASURED where AVexpectep is the expected change in voltage AV yeasurep 18 the measured change in voltage Fc is the correction factor 3 Multiply subsequent voltage measurements by the correction factor Fc to correct for any gain error present in the DAQ system Shunt Calibration Using the SCC SG11 The SCC SG11 shunt calibration module label displays the icon shown in Figure 15 This icon label also represents the shunt calibration confi
19. cy of the measurements e Sensitivity at 1 000 us is 0 5 mVoy7 Vey input e Used with the SCC SG01 02 National Instruments Corporation 41 SCC SG Series Strain Gage Modules User Guide Quarter Bridge Type II This section provides information for the quarter bridge strain gage configuration type II The quarter bridge type II measures either axial or bending strain Axial Bending Figure 25 Quarter Bridge Type II Measuring Axial and Bending Strain A quarter bridge type II has the following characteristics One active strain gage element and one passive temperature sensing quarter bridge element dummy strain gage The active element is mounted in the direction of axial or bending strain The dummy strain gage is mounted in close thermal contact with the strain specimen but not bonded to the specimen and is usually mounted transversely perpendicular to the principle axis of strain This configuration is often confused with the more commonly used half bridge type I configuration with the difference being that in the half bridge type I configuration the R element is active and bonded to the strain specimen to measure the effect of Poisson s ratio Completion resistors provide half bridge completion Compensates for temperature Sensitivity at 1 000 us is 0 5 mVoy7 Vey input Used with the SCC SG03 Dummy strain gage R provides quarter bridge completion SCC SG Series Strain Gage Modules User Guid
20. drive 60 mA Short circuit protection Yes Temperatureideft eects 10 ppm C ele 0 5 MV ms typ Power Requirements Analog power 340 mW max Ri A DOR SE 11 4 mA max SNS CA RE 11 4 mA max Digital power 930 mW max SN DO srs E E 186 mA max Operating voltage range TIS VDC penens saio deed tino 10 JS VDG ticki aie 10 FS d ELE 5 SCC SG11 Shunt Calibration Module Digital 1 0 Number of channels 1 Shunt Calibration Number of channels 2 Resistor for each channel 301 kQ 1 socketed Resistor temperature coefficient 100 ppm C Max voltage across channel 12 VDC Excitation current drive assumes two full bridge 350 Q configurations SCC SG Series Strain Gage Modules User Guide 34 ni com Power Requirements Analog power 0 1 mW max HIS AND ege Aer 5 UA max A5 KEE 5 HA max Digital power 25 uW TES VDC inks idee Sees 5 UA max Operating voltage range SEIN VDC signed 10 15 A RL 10 e EE 5 SCC SGXX Strain Gage Input Modules Maximum Working Voltage Maximum working voltage refers to the signal voltage plus the common mode voltage Channel to earth eo eee eeeeeeeeeeneeeeee 12 VDC Installation Category I Module to module 12 VDC Installation Category I Channel to channel 12 VDC Installation Category I Physical DIMENSIONS ccccccceceecceeeeeeses
21. e 42 ni com Half Bridge This section provides information for the half bridge strain gage configuration type I The half bridge type I measures either axial or bending strain Bending Figure 26 Half Bridge Type Measuring Axial and Bending Strain A half bridge type I has the following characteristics e Two active strain gage elements One is mounted in the direction of axial strain the other acts as a Poisson gage and is mounted transversely perpendicular to the principal axis of strain e Completion resistors provide half bridge completion e Sensitive to both axial and bending strain e Compensates for temperature e Compensates for the aggregate effect on the principle strain measurement due to the Poisson s ratio of the specimen material e Sensitivity at 1 000 ue is 0 65 mVoy7 Vey input e Used with the SCC SGO3 O National Instruments Corporation 43 SCC SG Series Strain Gage Modules User Guide Half Bridge II This section provides information for the half bridge strain gage configuration type II The half bridge type II only measures bending strain Bending Figure 27 Half Bridge Type II Rejecting Axial and Measuring Bending Strain A half bridge type II configuration has the following characteristics e Two active strain gage elements One is mounted in the direction of bending strain on one side of the strain specimen top the other is mounted in the direction of bendi
22. e the following equation EECH GEI v 2U v 1 Half Bridge Type II To convert voltage readings to strain units use the following equation 2V Ry strain GF sl g To simulate the effect on strain of applying a shunt resistor across R4 use the following equation e SC i GF SCC SG Series Strain Gage Modules User Guide 28 ni com Full Bridge Type To convert voltage readings to strain units use the following equation V r strain GF To simulate the effect on strain of applying a shunt resistor across R4 use the following equation Full Bridge Type Il To convert voltage readings to strain units use the following equation GE strain e GF v To simulate the effect on strain of applying a shunt resistor across Ry use the following equation E _ 2U GF v Full Bridge Type Ill To convert voltage readings to strain units use the following equation A strain GFIV 1 V 0 DI To simulate the effect on strain of applying a shunt resistor across Ry use the following equation 4U amp GFI UGS 1 For more information about configuring the SCC SG module using NI DAQmx refer to the SCC Quick Start Guide National Instruments Corporation 29 SCC SG Series Strain Gage Modules User Guide Specifications These ratings are typical at 25 C unless otherwise stated Sy Note Due to functional and electrical differences between the SCC SG
23. eseeeeeeees 8 89 cm x 2 92 cm x 1 85 cm 3 50 in x 1 15 in x 0 73 in WOLD es PRE NR RR RR ER 37 g VO Connectors essi eect geed geesde One 20 pin right angle male connector One 6 pin screw terminal Screw Terminal 28 to 16 AWG Resistor sockets Connecting lead size 0 023 to 0 026 in Connecting lead length 0 110 to 0 175 in Lead spacing csiis 0 500 in National Instruments Corporation 35 SCC SG Series Strain Gage Modules User Guide Safety Environmental Operating temperature sseseeeeeeeeeeeee O to 50 C Storage Temperature eee 20 to 70 C Relative humidity oe 10 to 90 noncondensing Maximum altitude 2 000 m Pollution Degree indoor use only 2 This product is designed to meet the requirements of the following standards of safety for electrical equipment for measurement control and laboratory use e TEC 61010 1 EN 61010 1 e UL3111 1 UL 61010B 01 e CAN CSA C22 2 No 1010 1 Ei Note For UL and other safety certifications refer to the product label or visit ni com hardref ost search by model number or product line and click the appropriate link in the Certification column Electromagnetic Compatibility Emseiong EN 55011 Class A at 10 m FCC Part 15A above 1 GHz Emily E EN 61326 1997 A2 2001 Table 1 CE C Tick and FCC Part 15 Class A Compliant EI Note For EMC compliance operate this device with shielded cabling CE Co
24. ge Modules User Guide Quarter Bridge Type II This section provides information for the quarter bridge strain gage configuration type II The quarter bridge type II measures either axial or bending strain Sy Note The quarter bridge temperature compensating element dummy strain gage adds an additional strain gage element to the quarter bridge type II that is not present in the quarter bridge type I You must use the half bridge completion on the SCC SGO3 for the quarter bridge type II to function properly Figure 8 shows a general quarter bridge type II circuit diagram D WW Figure 8 Quarter Bridge Type II Circuit Diagram The following symbols apply to the circuit diagram and equations e Ru and R are a half bridge completion resistors e R is the quarter bridge temperature compensating element dummy strain gage e Ry is the active element measuring tensile strain Figure 9 shows how to set up two quarter bridge type II configurations with the SCC SG03 You connect a quarter bridge type II to the SCC SG03 the same way you connect a half bridge configuration to the SCC SG03 SCC SG Series Strain Gage Modules User Guide 12 ni com R4 Al X 6 N 2 5V Ra Half Bridge Completion Reference 2 5V 5 No Eua Reserved O Connect Trimming V R Potentiometer NULL Al X 8 D 4 A 2 5V Half Bridge Com
25. guration using the SCC SG11 with the SCC SGOX or SCC SG24 SCAL Figure 15 SCC SG11 Icon Connecting the SCC SG11 Shunt Resistors Install the SCC SG11 according to the instructions in the Installing the Module section Connect the shunt calibration circuits as shown in Figures 16 17 or 18 depending on the bridge configuration National Instruments Corporation 19 SCC SG Series Strain Gage Modules User Guide SCC SG01 02 Al X O 6 R X 5 DAQ Device T O Al X 4 R4 S SP Two Wire 2 5V Vext 2 A S Half Bridge 1 Completion O MM Reference 1 v SCC SG11 elt Q 4 3 S AN SCAL Po x Q 2 0 i d O vw Figure 16 Quarter Bridge Shunt Calibration Configuration Using SCC SG11 and SCC SG01 02 One Channel to Shunt R4 SCC SG Series Strain Gage Modules User Guide 20 ni com SCC SG03 Al X lt 6 O Ry MP 4 SP SS v Z lt N 25V Ra Vext S 2 Half Bridge Mice Completion EX O 1 Reference 3 V analog Ground Z SCC SG11 Q 4 o a d S ANY S Was Po x S fe po amp O ANN Figure 17 Half Bridge Shunt Calibration Configuration Using SCC SG11 and SCC SGO3 One Channel to Shunt R O National Instruments Corporation 21 SCC SG Series Strain Gage Modules User Guide
26. idge type II configuration has the following characteristics e Four active strain gage elements Two are mounted in the direction of bending strain with one on one side of the strain specimen top the other on the opposite side bottom The other two act as Poisson gages and are mounted transversely perpendicular to the principal axis of strain with one on one side of the strain specimen top the other on the opposite side bottom e Rejects axial strain e Compensates for temperature e Compensates for the aggregate effect on the principle strain measurement due to the Poisson s ratio of the specimen material e Compensates for lead resistance e Sensitivity at 1 000 us is 1 3 mVour Vegy input e Used with the SCC SG04 24 SCC SG Series Strain Gage Modules User Guide 46 ni com Full Bridge Type Ill This section provides information for the full bridge strain gage configuration type III The full bridge type III only measures axial strain Bending Figure 30 Full Bridge Type III Measuring Axial and Rejecting Bending Strain A full bridge type III configuration has the following characteristics National Instruments Corporation Four active strain gage elements Two are mounted in the direction of axial strain with one on one side of the strain specimen top the other on the opposite side bottom The other two act as Poisson gages and are mounted transversely perpendicular to the principal axis
27. in task or global channel You also can scale the voltages manually in your application using the voltage to strain conversion equations provided in this document for each configuration type Finally there are voltage to strain conversion functions included in LabVIEW and NI DAQmx In LabVIEW the conversion function VI is in the Data Acquisition Signal Conditioning subpalette For text based programming ADEs the prototypes for the NI DAQ functions Strain_Convert and Strain_Buf_Convert are in the header file convert h for C C and convert bas for Visual Basic Refer to the NI DAQmx Help and the LabVIEW Measurements Manual for more information National Instruments Corporation 25 SCC SG Series Strain Gage Modules User Guide The names given to the strain gage types in this section directly correspond to bridge selections in MAX and the LabVIEW Convert Strain Gage Reading VI If you have not configured the SCC SGOX or SCC SG24 as an accessory for the E Series DAQ device as described in the Calibration section or if you are using the Macintosh operating system you must divide voltage measurements by 100 before converting them to units of strain This calculation accounts for the gain of 100 applied by each SCC SGOX or SCC SG24 channel If you have not configured the SCC SGOX or SCC SG24 or you are using the Macintosh operating system you cannot use virtual channels within the Data Neighborhood of MAX to convert voltage measureme
28. ing Adjustment The SCC SGOX and SCC SG24 have circuitry for offset nulling adjustment of bridge configuration circuits The nulling circuitry uses the excitation voltage as a reference and operates with quarter half and full bridge configurations Each channel has its own nulling circuit with a trimming potentiometer to adjust the nulling voltage level These potentiometers are accessible on the top of the SCC and are marked X for AI X offset nulling and X 8 for AI X 8 offset nulling The offset nulling circuitry has the added advantage of nulling the offset voltages of the entire signal path including the bridge configuration the SCC channel and the E Series DAQ device analog input channel Sy Note By factory default the nulling resistors are not installed in the SCC SG24 Refer to the Replacing Resistors section for information on installing the nulling resistors Nulling Range Adjustment The nulling range of the offset nulling adjustment circuitry for the SCC SGOX and SCC SG24 is referred to input RTI and given in Table 3 The nulling range figures assume a 30 kQ nulling resistor and an excitation voltage of 2 5 VDC for the SCC SGOX and 10 VDC for the SCC SG24 Table 3 SCC SGOX and SCC SG24 Nulling Ranges Active Strain Gage SCC Module Element Value Nulling Range SCC SG01 120 Q 2 5 mV SCC SG02 03 04 350 Q 6 6 mV SCC SG24 350 Q 29 mV 1 Calculated relative to the input range of the module
29. ing strain Figure 3 shows a general quarter bridge type I circuit diagram Figure 3 Quarter Bridge Type Circuit Diagram SCC SG Series Strain Gage Modules User Guide 8 ni com The following symbols apply to the circuit diagram and equations e RyandR are half bridge completion resistors e R is the socketed quarter bridge completion resistor dummy resistor e Ry is the active element measuring tensile strain 8 Figure 4 shows how to set up two quarter bridge type I configurations with the SCC SG01 02 Al X 6 P L 25V Half Bridge Completion gt Ra R X 5 R3 Reference 2 5V Three Wire O Hw Trimming Potentiometer V Rwutt i Al X 8 4 D s len P A 25V ae Half Bridge Completion R Reference 25V 3 Ta l e R X 8 VVV V Trimming Potentiometer V Rutt 2 A 25V Vex S 1 Reserved 2 Se Analog Ground R4 Strain Gage Active Element Rnutt Nulling Resistor Rs Quarter Bridge Completion Resistor National Instruments Corporation 9 Figure 4 SCC SG01 02 Quarter Bridge Configuration Connection Two Channels Connect the two wire strain gage element leads to AI X and Vgx For a three wire strain gage connect the two wire lead to AI X and R X then connect the single lead to Net Figure 4 shows two quarter bridge configurations using AI X and AI X 8 with a three wire strain g
30. lling range but makes the trimming potentiometers less sensitive when you adjust them Replacing the Shunt Resistors The shunting resistors Rscar on the SCC SG11 have a 301 KQ 1 value To replace a shunting resistor on the SCC SG11 complete the following steps 1 2 3 4 Remove the screw from the back wide unlabeled side Turn the front wide labeled side toward you Place the screw terminal receptacle to the left Slide the top cover to the right SCC SG Series Strain Gage Modules User Guide 24 ni com 5 Lift off the cover 6 Locate the shunting resistor and replace it Refer to Figure 21 to locate the shunting resistor on the SCC SG11 J dst Vai NATIONAL o ASSY1861764 01 B Of HO PP INSTRUMENTS COPYRIGHT 1999 O ee Fy Gp SCC SEU O Bs Dat 20900000000 O H ES FE 0000000000 v lo Ji O4 Ra FO 1 R1 Shunting Resistor Connected 2 R4 Shunting Resistor Connected to Pins 3 and 4 to Pins 1 and 2 Figure 21 SCC SG11 Parts Locator Diagram Using the SCC SGXX This section provides information about how to ensure your readings are properly scaled and converted to the correct units Converting Voltage Measurements to Units of Strain After you have acquired the voltage signal Mon you can scale this voltage to the appropriate strain units in software This is done automatically for you in NI DAQm x using a stra
31. lling the nulling resistors Figure 10 SCC SG04 24 Icon Full Bridge Type This section provides information for the full bridge strain gage configuration type I The full bridge type I only measures bending strain Figure 11 shows a general full bridge type I circuit diagram Figure 11 Full Bridge Type Circuit Diagram SCC SG Series Strain Gage Modules User Guide 14 ni com The following symbols apply to the circuit diagram and equations e Ryis an active element measuring compressive strain e R is an active element measuring tensile strain re e R is an active element measuring compressive strain LE e Ry is an active element measuring tensile strain Figure 14 shows how to set up two full bridge type I configurations with the SCC SG04 24 Full Bridge Type II This section provides information for the full bridge type II strain gage configuration The full bridge type II only measures bending strain Figure 12 shows a general full bridge type H circuit diagram Figure 12 Full Bridge Type II Circuit Diagram The following symbols apply to the circuit diagram and equations e R is an active element measuring compressive Poisson effect ve e Rj is an active element measuring tensile Poisson effect ve e Rgis an active element measuring compressive strain e Ry is an active element measuring tensile strain re Fig
32. mpliance This product meets the essential requirements of applicable European directives as amended for CE marking as follows Low Voltage Directive safety 73 23 EEC Electromagnetic Compatibility Directive EMU 89 336 EEC SCC SG Series Strain Gage Modules User Guide 36 ni com B Note Refer to the Declaration of Conformity DoC for this product for any additional regulatory compliance information To obtain the DoC for this product visit ni com hardref nsf search by model number or product line and click the appropriate link in the Certification column SCC SGXX Module Pin Assignments Figure 22 shows the I O connector pins on the bottom of the module ODOODODDOOO DOGDDODOO OO Figure 22 SCC Module Bottom View Table 1 lists the signal connection corresponding to each pin AI X and AI X 8 are the analog input signal channels of the E Series DAQ device AI GND is the analog input ground signal and is the reference for AI X and AI X 8 A GND is the reference for the 15 V supplies and REF 5 V AI GND and A GND connect to the SC 2345 at the SCC PWR connector GND is the reference for the 5 V supply National Instruments Corporation 37 SCC SG Series Strain Gage Modules User Guide Table 1 Pin Signal Connections for SCC SGXX Pin Number SGXX Signal SG11 Signal 1 DAQ device AI X
33. must supply additional wires as described in this section and shown in Figures 16 17 and 18 Replacing Resistors The SCC SGXX all have socketed resistors so you can easily replace them A typical 1 4 W size resistor should fit in the socket Refer to the Specifications section for socket dimensions Replacing the Quarter Bridge Completion Resistors To replace a quarter bridge completion resistor on the SCC SG01 02 complete the following steps Oy o es eg Remove the screw from the back wide unlabeled side Turn the front wide labeled side toward you Place the screw terminal receptacle to the left Slide the top cover to the right Lift off the cover Locate the completion resistor and replace it with a resistor that matches the value of the strain gage element actively measuring strain Refer to Figure 19 to locate the completion resistor Ee Re R3 L Q E Ea Jt Cag le oO Sei KS 2000 FO Ege GE Sg O c800000600 O prs s oo umf 0000000000 O orga db E ap 0 0 0o H kel ECO ECO oO T a al Do A ly OO E oh R9 Quarter Bridge Completion Resistor for Al X SCC SGO1 and SCC SGO2 only R5 Nulling Resistor for Al X 8 R1 Nulling Resistor for Al X R6 Offset Nulling Adjustment for Al X R7 Offset Nulling Adjustment for Al X 8 R19 Quarte
34. n Half Bridge Type This section provides information for the half bridge strain gage configuration type I The half bridge type I measures either axial or bending strain SCC SG Series Strain Gage Modules User Guide 10 ni com Figure 6 shows a general half bridge type I circuit diagram D WW Figure 6 Half Bridge Type Circuit Diagram The following symbols apply to the circuit diagram and equations e RyandR are half bridge completion resistors e R is the active element measuring compression from Poisson effect ve e Ry is the active element measuring tensile strain 8 Figure 9 shows how to set up two half bridge type I configurations with the SCC SG03 Half Bridge Type II This section provides information for the half bridge strain gage configuration type II The half bridge type II only measures bending strain Figure 7 shows a general half bridge type II circuit diagram 3 R e Aa R 3 Ra 8 Figure 7 Half Bridge Type II Circuit Diagram The following symbols apply to the circuit diagram and equations e R and R are half bridge completion resistors e R is the active element measuring compressive strain 8 e R4is the active element measuring tensile strain 8 Figure 9 shows how to set up two half bridge type II configurations with the SCC SG03 National Instruments Corporation 11 SCC SG Series Strain Ga
35. nd company names mentioned herein are trademarks or trade names of their respective companies For patents covering National Instruments products refer to the appropriate location Help Patents in your software the patents txt file on your CD or agua io Seen y 371073B 01 Mar04 ni com patents 2002 2004 National Instruments Corp All rights reserved
36. ng strain on the opposite side bottom e Completion resistors provide half bridge completion e Sensitive to bending strain e Rejects axial strain e Compensates for temperature e Sensitivity at 1 000 ue is 1 mV oyr Vegy input e Used with the SCC SGO3 SCC SG Series Strain Gage Modules User Guide 44 ni com Full Bridge Type This section provides information for the full bridge strain gage configuration type I The full bridge type I only measures bending strain Bending Figure 28 Full Bridge Type Rejecting Axial and Measuring Bending Strain A full bridge type I configuration has the following characteristics e Four active strain gage elements Two are mounted in the direction of bending strain on one side of the strain specimen top the other two are mounted in the direction of bending strain on the opposite side bottom e Highly sensitive to bending strain e Rejects axial strain e Compensates for temperature e Compensates for lead resistance e Sensitivity at 1 000 us is 2 0 mVoy7 Vex input e Used with the SCC SG04 24 National Instruments Corporation 45 SCC SG Series Strain Gage Modules User Guide Full Bridge Type II This section provides information for the full bridge type II strain gage configuration The full bridge type II only measures bending strain Bending Figure 29 Full Bridge Type II Rejecting Axial and Measuring Bending Strain A full br
37. nts into units of strain To convert properly scaled voltage measurements to units of strain complete the following steps 1 Read the bridge configuration channel on the E Series DAQ device Veseries AI OO 2 Calculate the voltage by using the following formula Vso VEsERIES 100 where Vg is the bridge configuration voltage Veseries is the E Series DAQ device voltage This calculation provides proper scaling for the amplifier in the SCC SGOX and SCC SG24 Ei Note The SCC SGOX built in excitation voltage is 2 5 VDC The SCC SG24 excitation voltage is 10 VDC Strain Equations This section provides the equations used to convert voltage readings to units of strain and simulate the effect of a shunt resistor Ei Note If you are not using NI software or you are using the Macintosh operating system you can use these equations in your software application to properly scale your measurements SCC SG Series Strain Gage Modules User Guide 26 ni com Formulas and Variable Definitions In the equations in this document the following formulas and variable definitions are used Se is the simulated strain GF is the Gage Factor which should be specified by the gage manufacturer R is the nominal gage resistance which should be specified by the gage manufacturer R is the lead resistance If lead lengths are long R can significantly impact measurement accuracy ei Note You can neglect the R of the wiring if shunt cali
38. pletion Reference L 2 5V 3 No SC Reserved Connect Trimming V R Potentiometer NULL 2 L 25V 1 V Analog Ground R Strain Gage Active Element Ryuu Nulling Resistor Rs Quarter Bridge Completion Resistor or Temperature Compensating Element Figure 9 SCC SGOS3 Half Bridge Configuration Connection Two Channels Use three lead wires to connect the strain gages to screw terminals Vpy Vex and AI X The pair of wires connected to Vgx and Vex provide excitation voltage to the strain gage The other wire connected to AI X senses the output voltage of the strain gage with respect to the internal half bridge completion reference Figure 9 shows two half bridge configurations using AI X and AI X 8 National Instruments Corporation 13 SCC SG Series Strain Gage Modules User Guide SCC SG04 24 Full Bridge Connection In a full bridge configuration you use four active strain gage elements in the bridge configuration with all of the elements external to the SCC module There are three full bridge configuration types supported by NI software The following sections describe how to connect full bridge configuration types I II and HI The SCC SG04 24 module labels display the icon shown in Figure 10 These icon labels also represent the bridge configuration of the modules 3 Note By factory default the nulling resistors are not installed in the SCC SG24 Refer to the Replacing Resistors section for information on insta
39. r Bridge Completion Resistor for Al X 8 SCC SGO1 and SCC SGO2 only National Instruments Corporation Figure 19 SCC SGOX Parts Locator Diagram 23 SCC SG Series Strain Gage Modules User Guide Replacing the Nulling Resistors To replace a nulling resistor on the SCC SGOX or SCC SG24 complete the following steps Noe So ye Remove the screw from the back wide unlabeled side Turn the front wide labeled side toward you Place the screw terminal receptacle to the left Slide the top cover to the right Lift off the cover Locate the nulling resistor and replace it Refer to Figures 19 and 20 to 10O O Be O S RIS o 5300 d S a locate the nulling resistors 2 i 7 R39 R40 O ol o o lo TX O OR HO O 00a STA so a moon ll SE 000000000 O abet NEE E 0000000000 O To 3 O 2 cones C200 CS ES R C 2 om o D R24 t ciz c13 D 280000 Oe on CIA Cp J1 DIO DD CH E O ed GO A R5 Nulling Resistor for Al X 8 R1 Nulling Resistor for Al X R39 Offset Nulling Adjustment for Al X R40 Offset Nulling Adjustment for Al X 8 Figure 20 SCC SG24 Parts Locator Diagram Ei Note Replacing a nulling resistor can give you a larger nu
40. ridge configurations Variable Definitions In the following figures the variables are defined as is the measured strain e is tensile strain and e is compressive strain v is the Poisson s ratio defined as the negative ratio of transverse strain to axial longitudinal strain Vcy is the measured voltage of the signal Vex is the excitation voltage SCC SG01 02 Quarter Bridge Connection In a quarter bridge configuration you use only one active strain gage element The following section describes how to connect a quarter bridge strain gage configuration type I Sy Note NI software supports two quarter bridge configuration types However to measure the quarter bridge configuration type II you must use the SCC SG03 Refer to the SCC SG03 Half Bridge Connection section for more information O National Instruments Corporation 7 SCC SG Series Strain Gage Modules User Guide The SCC SG01 module label displays the icon shown in Figure 1 and the SCC SG02 module label displays the icon shown in Figure 2 These icon labels also represent the bridge configurations of the modules On the SCC SGXX module labels the boxed resistors represent external active strain gage elements Q Figure 1 SCC SGO1 Icon No Figure 2 SCC SGO2 Icon Quarter Bridge Type This section provides information for the quarter bridge strain gage configuration type I The quarter bridge type I measures either axial or bend
41. rs SCC refers to any SCC Series signal conditioning module SCC SG Series Strain Gage Modules User Guide 4 ni com SCC SGOX SCC SGOX refers to SCC SG Series strain gage input modules SGO1 SOU SG03 and SG04 SCC SGXX SCC SGXX refers to any SCC SG series strain gage module What You Need to Get Started To set up and use the SCC SGXX you need the following items Q SC 2345 2350 with one of the following SCC PWRO1 SCC PWRO02 and the PSO1 power supply SCC PWRO3 requires a 7 to 42 VDC power supply not included One or more SCC SGXX SCC SG Series Strain Gage Modules User Guide SC 2345 2350 User Manual available at ni com SCC Quick Start Guide available at ni com Read Me First Safety and Radio Frequency Interference SC 2345 Quick Reference Label COovovovoO DD 68 pin Basic or E Series DAQ device documentation and 68 pin cable 1 8 in flathead screwdriver Numbers 1 and 2 Phillips screwdrivers Wire insulation strippers Coo vo NI DAQ current version for Windows 2000 NT XP Me ei Note Software scaling of measurements is not supported on the Macintosh operating system Refer to the Converting Voltage Measurements to Units of Strain section for more information O National Instruments Corporation 5 SCC SG Series Strain Gage Modules User Guide Device Specific Information 3 Note For general SCC module installation and signal connection information and information about the SC 235
42. ry default the nulling resistors are not installed in the SCC SG24 Refer to the Replacing Resistors section for information on installing the nulling resistors To nullify the offset error values with trimming potentiometers located on the module refer to the Calibration section or negate the values in your software application SCC SG Series Strain Gage Modules User Guide 32 ni com Amplifier Characteristics Common mode rejection ratio CMRR EE 110 dB min Output range iein 10 VDC max Input impedance Common mode 5 MQ Differential A 20 MQ Powered off or overload gt 60 KQ Input bias ceurent 10 nA max Input offset current 10 nA max Dynamic Input noise 0 1 to 10 Hz 0 4 HN uns 2 5 UV pp Input Dee eebe Eeer 3 UVims 25 UV pp Stability Recommended warm up time 5 min Ee asi ira ses lins 10 ppm C max Offset error temperature coefficient 4 uV C max Null Compensation Radeon TA derer cen ant ete 0 29 of excitation range 29 mV or 2 900 ue null compensation range AV e SU 2 900 VexO where Vour is the output voltage range of 58 mV Vex is the excitation voltage of 10 VDC Gr is 2 0 1 Temperature range is 0 to 50 C National Instruments Corporation 33 SCC SG Series Strain Gage Modules User Guide Excitation Number of channels 1 Level sd beste dn tthe nari deeg Dna 10 VDC 0 05 Current
43. tion reference Temperature range is 0 to 50 C 2 Excitation current drive assumes two full bridge 120 Q configurations National Instruments Corporation 31 SCC One 120 Q 1 4 W 0 1 tolerance 10 ppm C or One 350 Q 1 4 W 0 1 tolerance 10 ppm C Two 10 kQ 0 02 ratio tolerance 2 ppm C tracking temperature coefficient of resistance resistors 1 25 VDC 0 4 SG Series Strain Gage Modules User Guide Power Requirements Analog power 143 mW max HUD VDG isegi ete 4 75 mA max 15 VDC Bu dama ecoa 4 75 mA max Digital power wicicssccsccsctesessevssceassensecesebes 210 mW max F3 VDC rareori nea enaA 42 mA max Operating voltage range RAI VIDE onsena 10 A AR 10 SEDA E 5 RER VDC uses sms arise 0 05 SCC SG24 Strain Gage Input Module Analog Input Number of strain gage channels 2 DIFF Input signal ranges ce eeeeeeeeeeeecereeees 100 mV fixed gain of 100 on each channel Strain gage bridge configuration Full bridge Overvoltage protection 42 VDC powered on and powered off Inputs protected lt 0 1 gt Transfer Characteristics GA EE 100 CHE EE 0 20 of reading max Offset MOP ss siete oti doa 50 uV typ 325 uV max before calibration Nonlinearity 0 0 eseeeeeeeeeeeees 200 ppm max of full scale range Bandwidth Steeg ENEE dee 1 6 kHz single pole buffered RC filter By facto
44. ure 14 shows how to set up two full bridge type II configurations with the SCC SG04 24 National Instruments Corporation 15 SCC SG Series Strain Gage Modules User Guide Full Bridge Type III This section provides information for the full bridge strain gage configuration type III The full bridge type III only measures axial strain Figure 13 shows a general full bridge type III circuit diagram Figure 13 Full Bridge Type III Circuit Diagram The following symbols apply to the circuit diagram and equations e Riis an active element measuring compressive Poisson effect ve e Rj is an active element measuring tensile strain e Ris an active element measuring compressive Poisson effect ve e Ry is an active element measuring the tensile strain e Figure 14 shows how to set up two full bridge type HI configurations with the SCC SG04 24 SCC SG Series Strain Gage Modules User Guide 16 ni com Al X 2 5V Al X 5 ne Trimming R 2 Potentiometer NULL Al X 8 4 DO Al X 8 gt Trimming Potentiometer 2 RNULL 1 A25V YW Da a N Vex V Analog Ground 1 The SCC SG24 provides a 10 VDC excitation current 2 By factory default the nulling resistors are not installed in the SCC SG24 Figure 14 SCC SG04 24 Full Bridge Configur
45. vices usually 10 VDC Excitation The SCC SGOX and SCC SG24 contain a single onboard voltage source for bridge configuration excitation On the SCC SGOX the onboard regulated 2 5 VDC excitation source supplies up to 42 mA which is enough to drive two 120 Q full bridge configurations The SCC SG24 has an onboard regulated 10 VDC excitation source that supplies up to 60 mA which is enough to drive two 350 Q full bridge configurations Optionally you can connect an external excitation source of up to 15 VDC across the bridge configurations If the external excitation source is not ground referenced connect its negative terminal to Vrx If the external excitation source is ground referenced and you connect the negative terminal to Vgx a ground loop could result that can damage the SCC SGOX and SCC SG24 External excitation must not exceed 15 VDC SCC SG Series Strain Gage Modules User Guide 48 ni com Bridge Completion The SCC SG01 02 come with quarter bridge completion resistors that complete the bridge configuration The quarter bridge completion resistors are socketed so that you can replace them Refer to the Replacing Resistors section for more information on replacing resistors Only replace them with resistors that match the value of the strain gage element actively measuring strain By default the SCC SG01 02 quarter bridge completion resistor value is 120 Q and 350 Q respectively Theory of Calibration Of set Null
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